General Atomics, Inc.

Frederick H Elsner

Lawrence D Woolf

William A Raggio

Clyde H Shearer

Tihiro Ohkawa

Khodabakhsh S Mazdiyasni

Barry W McQuillan

Michael V Fisher

Richard B Stephens

Debra J Treacy

Methods for making fiber-reinforced carbon, ceramic or metal matrix composites using electrophoretic infiltration of an array or preform of electrically insulating fibers positioned adjacent a target electrode in an appropriate liquid slurry. The slurry contains a dispersion of micron- or submicron-sized particles, usually of elemental or ceramic materials, which are suitably electrically charged in the slurry, employing a surfactant if necessary. Application of an appropriate voltage causes charged particles to migrate toward the target electrode following a path that causes them to infiltrate the interstices of the fiber array which is usually formed of woven or aligned tows of minute fibers about 5 to 15 microns in diameter. The particles initially deposit on the electrode with subsequent particles aggregating on top of those particles, the process continuing to form a growth front of deposited material growing away from the electrode surface. The resultant deposit of aggregating particles grows through the interstices of the fibrous preform from one surface of the preform to the other, filling voids with matrix material. Following such infiltration, the impregnated particles are consolidated by hot-pressing and/or by subjection to CVI.

Fabrication of fiber-reinforced composites

A superconducting structure is provided comprising a substrate, a superconductor coating supported by the substrate and a diffusion barrier positioned between the superconductor coating and the substrate to inhibit diffusion of contaminants from the substrate to the superconductor coating. The coating is a ceramic oxide having superconducting properties. The diffusion barrier may likewise be a ceramic oxide, but differs in its specific composition to provide it with a peritectic decomposition temperature greater than the superconductor coating. Accordingly, the diffusion barrier exhibits substantially lower atomic mobility than the superconductor coating during manufacture of the superconducting structure, thereby preventing contamination of the coating by the substrate.

Contaminant diffusion barrier for a ceramic oxide superconductor coating

A ceramic superconductor comprises a substantially nonmagnetic preannealed nickel-based alloy substrate which supports a ceramic superconductor. The substrate may include aluminum to strengthen the substrate, make it less magnetic and enhance its chemical compatibility with the ceramic superconductor. The ceramic is formed on the substrate by sintering superconductor grains at temperatures above 1000.degree. C. to enhance densification of the ceramic.

Nickel-based substrate for ceramic superconductor

A process for preparing a superconductor-coated substrate including calcining a mixture of powdered yttrium or rare earth oxide (R), barium carbonate and copper oxide in a controlled atmosphere and in accordance with a predetermined temperature profile to form a superconductor powder having a stoichiometric ratio of R-Ba-Cu of approximately 1-2-3. The melting transition width of the resulting powder is relatively narrow, such that the melting onset temperature is above the high temperatures advantageously used to sinter the powder on the substrate.

Production of a superconductor powder having a narrow melting transition

A method for the manufacture of superconducting polycrystalline ceramic materials by the decomposition of a mixture of isopropoxides.

Manufacture of high purity superconducting ceramic

A process for joining ceramic superconductor fibers with a channel to fabricate a superconductor wire includes feeding the fibers into the channel and continuously dispensing a flowable solder paste into the channel over the fibers. The combination of channel, fibers and solder paste is then subjected to a rapid rise in temperature which sequentially activates the flux in the solder paste and then melts the solder. After the workpiece is cooled and the separated flux has been removed, a superconductor wire has been fabricated.

Process for soldering superconducting fibers into a copper channel

A method and apparatus for manufacturing a superconductor wire has a wire take-up spool and a feed speed control spool. A wire substrate is taken from the feed speed control spool and onto the take-up spool as the wire take-up spool is rotated. The wire passes through a container which holds a diffusion barrier material, where the diffusion barrier material is electrophoretically deposited onto the wire substrate and subsequently sintered. The wire is also passed through a container which holds a superconductor material suspended in solution, and a layer of the superconductor material is electrophoretically deposited onto the diffusion barrier. The grains of the superconductor layer are then magnetically aligned and sintered. Also, a silver coating is electrophoretically deposited onto the superconductor layer and sintered. A diffusion bonding inhibitor material is then applied to the silver coating. Then, the silver-coated superconductor wire is spooled and heated to four hundred degrees centigrade (400.degree. C.) for (1) day to oxidize the superconductor layer.

Fabrication of silver coated high temperature ceramic superconductor

An aqueous and method for manufacturing a ceramic superconductor coated metal fiber comprises a container for holding a nonaqueous solution inwhich particles of superconductor material are colloidally suspended to form a slurry. A voltage source is provided to influence the slurry with an electric field and a magnet device is provided to influence the slurry with a magnetic field. The magnetic field is oriented relative to the fiber to align the superconductor particles of the slurry in a desired orientation for subsequent attachment onto the surface of the fiber. The voltage source is connected to the metal fiber to electrically bias the fiber as it is drawn through the slurry. Consequently, charged superconductor particles in the slurry attach to the electrically biased fiber. Subsequently, the coated fiber is heated to sinter the aligned particles and establish a ceramic superconductor shell on the metallic fiber substrate.

Apparatus and method for manufacturing a ceramic superconductor coated

A substrate for supporting a ceramic superconductor comprises a metallic base member precoated with an yttrium oxide, rare earth oxide, or zirconium oxide layer and having a constituent oxide former which establishes an oxide layer with the yttrium oxide, rear earth oxide, or zirconium oxide on the surface of the substrate. A layer of ceramic superconducting material covers the substrate with the oxide layer between the metallic base member and the ceramic superconductor layer to inhibit the interdiffusion of respective constituent elements between the metallic base member and the ceramic layer. For applications requiring the transmission of electrical current through the ceramic layer over relatively extensive distances, the substrate can be formed as a wire or ribbon.

Substrate for ceramic superconductor with improved barrier

A process for depositing a silver coating onto a superconductor involves placing the superconductor into an alcohol solution, preferably octanol, which contains silver particles. Each silver particle is coated with a layer of oleic acid. An electrode, preferably made of silver, is also disposed in the anhydrous solution. A direct current voltage is then established on the electrode, which causes the silver particles to plate onto the superconductor. After electrophoresis, the now-plated superconductor is heated to nine hundred degrees centigrade (900.degree. C.) for approximately one (1) minute.

Anhydrous electrophoretic silver coating technique

A substrate for supporting a ceramic superconductor comprises a metallic base member having a constituent oxide former which establishes an oxide layer on the surface of the substrate. A layer of ceramic superconducting material covers the substrate with the oxide layer between the metallic base member and the ceramic superconductor layer to inhibit the interdiffusion of respective constituent elements between the metallic base member and the ceramic layer. For applications requiring the transmission of electrical current through the ceramic layer over relatively extensive distances, the substrate can be formed as a wire.

Substrate for ceramic superconductor

A ceramic superconductor comprises a substantially nonmagnetic preannealed nickel-based alloy substrate which supports a ceramic superconductor. The substrate may include aluminum to strengthen the substrate and make it less magnetic. The substrate is substantially devoid of minority constitutent oxide shell formers and the ceramic is formed on the substrate by sintering superconductor grains at temperatures above 1000.degree. C. to enhance densification of the ceramic.

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Cardiff, CA, United States of America

Frederick H Elsner